Filters are used in the medical technical field as laboratory filters or for blood analysis, where special filter membranes are used for different tests. These filter membranes have to be exchanged quickly and frequently. Such filters are generally known and usually include a shell-shaped body as the bottom part of the housing, wherein the cover is connectable with the shell-shaped body by means of a thread forming a rotary closure. Since such filters have housings with a diameter of about 30 mm, the thread connection between the cover and the housing bottom part is extremely cumbersome, and additionally there is the danger that, when closing the rotary cover, the filter membrane can be deformed. The manufacture of the housings for such filters is comparatively difficult since rotary cores have to be used in the injection molding tools to enable to demold one of the two thread parts, i.e. the interior thread. The costs of the tools to be produced for this purpose are comparatively high.
Thus, it is desired to improve a filter of the above identified kind in such a way that the drawbacks of the prior art are avoided and that the production thereof is much more economical.